• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.505-510
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• 2014

The properties of black ceramic pigments including thermal and glaze stability were systematically investigated so that these pigments could be used to decorate porcelain products. Various compositions of $(Ni,Mn)(Fe,Cr,Mn)_2O_4$ and $Co(Fe,Cr)_2O_4$ powders were synthesised using a solid state reaction method. The obtained $Co(Fe,Cr)_2O_4$ and $(Ni,Mn)(Fe,Cr,Mn)_2O_4$ powders showed single phases of spinel structure after calcination processes at $1000^{\circ}C$ and $1200^{\circ}C$, respectively. CIE $L^*a^*b^*$ colourimetric parameters of glazed $Co(Fe,Cr)_2O_4$ and $(Ni,Mn)(Fe,Cr,Mn)_2O_4$ pigments were analyzed according to the different amounts of Cr substitution. In addition, the amount of $Cr^{+6}$ remaining in the $Co(Fe,Cr)_2O_4$ and $(Ni,Mn)(Fe,Cr,Mn)_2O_4$ pigments was also measured.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.787-796
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• 2009

The fracture toughness improvement of Ni-Mn-Ga-Fe ferromagnetic shape memory alloys containing ductile particles was explained by direct observation of microfracture processes using an in situ loading stage installed inside a scanning electron microscope (SEM) chamber. The Ni-Mn-Ga-Fe alloys contained a considerable amount of ductile particles in the grains after the homogenization treatment at $800{\sim}1100^{\circ}C$. ${\gamma}$ particles were coarsened and distributed homogeneously along {$\beta}$ grain boundaries as well as inside {$\beta}$ grains as the homogenization temperature increased. The in situ microfracture observation results indicated that ${\gamma}$ particles effectively acted as blocking sites of crack propagation, and provided stable crack growth that could be confirmed by the R-curve analysis. This increase in fracture resistance with increasing crack length improved overall fracture properties of the alloys containing ${\gamma}$ particles.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.91-95
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• 1998

Exchange anisotropy between IrMn antiferromagnetic layer and NiFe ferromagnetic layer has been studied in IrxMn(100-x)/NiFe/Buffr/Si(100) films deposited by D. C. magnetron sputtering method. Among Zr, Ta, and Cu used as buffer layer, Zr and Ta enhanced the fcc(111) texture of NiFe and IeMn layer, but Cu did not affect microstructure of those layer. Strong fcc(111) texture of IrMn layer was confirmed to be the origin of exchange anisotropy of IrMn. Ir composition control in IrMn layer showed that {{{{ gamma -phase}}}} IrMn is stabilized between 10 and 30 at % Ir, an 21 at. % Ir in IrMn layer was optimum composition that showed maximum exchange anisotropy field. above 200 ${\AA}$ thickness of IrMn, antiferromagnetic property is stabilzed to show saturated exchange anisotropy field. Based pressure was confirmed to be critical requisite in IrMn-based spin-valve GMR system.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.120-123
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• 2007

The typical double-barrier magnetic tunnel junction (DMTJ) structure examined in this paper consists of a Ta 45/Ru 9.5/IrMn 10/CoFe7/$AlO_x$/free layer/AlO/CoFe 7/IrMn 10/Ru 60 (nm). The free layer consists of an $Ni_{16}Fe_{62}Si_8B_{14}$ 7 nm, $Co_{90}Fe_{10}$ (fcc) 7 nm, or CoFe $t_1$/NiFeSiB $t_2$/CoFe $t_1$ layer in which the thicknesses $t_1$ and $t_2$ are varied. The DMTJ with an NiFeSiB-free layer had a tunneling magnetoresistance (TMR) of 28%, an area-resistance product (RA) of $86\;k{\Omega}{\mu}m^2$, a coercivity ($H_c$) of 11 Oe, and an interlayer coupling field ($H_i$) of 20 Oe. To improve the TMR ratio and RA, a DMTJ comprising an amorphous NiFeSiB layer that could partially substitute for the CoFe free layer was investigated. This hybrid DMTJ had a TMR of 30%, an RA of $68\;k{\Omega}{\mu}m^2$, and a of 11 Oe, but an increased of 37 Oe. We confirmed by atomic force microscopy and transmission electron microscopy that increased as the thickness of NiFeSiB decreased. When the amorphous NiFeSiB layer was thick, it was effective in retarding the columnar growth which usually induces a wavy interface. However, if the NiFeSiB layer was thin, the roughness was increased and became large because of the magnetostatic $N{\acute{e}}el$ coupling.

• Korean Journal of Metals and Materials
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• v.50 no.6
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• pp.419-425
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• 2012

The purpose of this research was to develop a low Ni austenitic cast iron through replacing Ni by Cu and Mn because they are cheaper than Ni. The effect of the Cu content (6-12 wt%) on the microstructure characteristics was investigated in Fe-3%C-16%(Ni+Cu+Mn) cast iron. Contrary to general effect of the Cu on cast iron, the result of the microstructure analysis indicated that bainite and cementite were formed in high Cu content (>8 wt%Cu). A crystallized Cu-solution (Cu-Mn) phase and MnS in the Cu-solution were formed. The quantity of those phases increased as the Cu content increased. Consequently, the high Cu content in the composition ratio (Ni+Cu+Mn=16%) caused the formation of Cu-Mn/MnS and those phases decreased the effect of Cu and Mn on austenite formation. For this reason, bainite and cementite were formed in high Cu content.

• Archives of Pharmacal Research
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• v.12 no.3
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• pp.214-218
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• 1989

Atmospheric particulate matters (A. P. M. ) were collected on quartz-fiber filters from March 1985 to May 1986, using the Andersen high-volume air sampler and contents of six heavy metals (Fe, Mn, Cu, Zn, Pb Ni) in the A. P. M. were determined by atomic absorption spectrophotometry. These heavy metals were divided into the three groups with respect to their particle size distribution. Fe and Mn were mainly associated with coarse particles (diameter > 2.0 $\mu$m), but Pb and Ni were related fine particles (diameter < 2.0 $\mu$m). Cu and Zn had mized size distributions in both of them. In the seasonal variation of heavy metals, the contents of Fe and Mn in spring and Ni and Pb in winter were higher than any other season. There were high mutual correlation between Fe and Mn coarse particles, and between Pb and Ni in fine particles.

• Korean Journal of Materials Research
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• v.23 no.7
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• pp.385-391
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• 2013

The influence of Cu and Ni on the ductile-brittle transition behavior of metastable austenitic Fe-18Cr-10Mn-N alloys with N contents below 0.5 wt.% was investigated in terms of austenite stability and microstructure. All the metastable austenitic Fe-18Cr-10Mn-N alloys exhibited a ductile-brittle transition behavior by unusual low-temperature brittle fracture, irrespective of Cu and/or Ni addition, and deformation-induced martensitic transformation occasionally occurred during Charpy impact testing at lower temperatures due to reduced austenite stability resulting from insufficient N content. The formation of deformation-induced martensite substantially increased the ductile-brittle transition temperature(DBTT) by deteriorating low-temperature toughness because the martensite was more brittle than the parent austenite phase beyond the energy absorbed during transformation, and its volume fraction was too small. On the other hand, the Cu addition to the metastable austenitic Fe-18Cr-10Mn-N alloy increased DBTT because the presence of ${\delta}$-ferrite had a negative effect on low-temperature toughness. However, the combined addition of Cu and Ni to the metastable austenitic Fe-18Cr-10Mn-N alloy decreased DBTT, compared to the sole addtion of Ni or Cu. This could be explained by the fact that the combined addition of Cu and Ni largely enhanced austenite stability, and suppressed the formation of deformation-induced martensite and ${\delta}$-ferrite in conjunction with the beneficial effect of Cu which may increase stacking fault energy, so that it allows cross-slip to occur and thus reduces the planarity of the deformation mechanism.

• Proceedings of the Korean Magnestics Society Conference
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• 1999.04a
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• pp.28-29
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• 1999

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.62.2-62
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• 2000

• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.98-99
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• 2002